Dentifrice compositions comprising dicalcium orthophosphate and sodium monofluorophosphate



United States Patent 3,308,029 DENTIFRICE COMPOSITIONS COMPRISING DI- CALCIUM ORTHOPHOSPHATE AND SODIUM MONOFLUOROPHOSPHATE Elerington Saunders, St. Louis, and Thomas Schrff, Clayton, Mo., assignors to Monsanto Company, a corporation of Delaware No Drawing. Filed Nov. 6, 1963, Ser. No. 321,689 4 Claims. (Cl. 167-93) The present invention relates to novel, valuable dentifrice compositions containing, as a source of fluorine, an alkali metal monofluorophosphate.

It has now been discovered that certain compositions containing an alkali 'metal monofluorophosphate as a source of fluorine and dicalcium orthophosphate as the abrasive are surprisingly compatible. The present invention is surprising in view of the fact that with practically all other sources of fluorine, dicalcium orthophosphate is one of the least compatible of all known dentifrice abrasives.

Although the dicalcium orthophosphate abrasive can be present in the dentifrice compositions of the present invention in either the anhydrous or dihydrate form, it is generally preferred that the dicalcium orthophosphate portion of the dentifrice composition of this invention be largely (i.e., at least about 50 Weight percent) the dihydrate (CaHPO -2H O). Still further preferred are those compositions wherein practically all of the dicalcium orthophosphate is present in the form of the dihydrate. In toothpastes, the level of the dicalcium orthophosphate, in accordance with the present invention, generally can be varied from about 20 to about 60 weight percent of the final toothpaste composition. While levels lower than about 20 weight percent can be used, generally at such lower levels of abrasive, cleaning efliciency of the paste drops sharply. Preferably the level of the dicalcium orthophosphate in such toothpaste should be between about 35 and about 50 Weight percent of the toothpaste composition. In tooth powders, generally higher amounts of dicalcium orthophosphates, for example often up to about 95 weight percent or more, can be utilized, based on the total weight of the final tooth powder composition. The dicalcium orthophosphate need not be the only abrasive material in the dentifrice composition of the present invention. Generally, however, it is preferred that dicalcium orthophosphate, in the form of the dihydrate and/ or the anhydrous material, represent at least about half of all of the abrasive materials in the dentifrice compositions of the present invention.

While the use of even very small amounts of alkali metal monofluorophosphate (preferably sodium monofluorophosphate) in the dentifrice compositions of the present invention is beneficial to at least a certain extent, it is generally preferred that at least about 0.2 weight percent of the alkali metal monofluorophosphate be formulated into the dentifrice compositions of the present in vention. For optimum results, however, taking into account the relative cost of the various ingredients, the relative non-toxicity of the monofluorophosphate (as compared with simple fluoride salts such as sodium fluoride), and the usual practice of those using dentifrice compositions of the same general type as the compositions of the present invention to clean their teeth (and simultaneously protect their teeth by reducing the incidence of dental caries), generally between about 0.5 and about 2 (and preferably from about 0.7 to about 0.8) weight percent of the alkali metal monofluorophosphate be present in the detifrice compositions of the present invention.

In the formulation of finished dentifrice compositions containing the dicalcium orthophosphate abrasive-alkali metal monofluorophosphate mixtures of this invention,

practically any of the auxiliary agents that are conveniently utilized in toothpastes and/or tooth powders can be utilized in conjunction with these novel mixtures. Toothpastes, for example, generally contain, in addition to the abrasive and the fluorine. source, a sweetener such as saccharin; a humectant such as sorbitol and/ or glycerin; a binding agent such as gum tragacanth, Irish moss extract, carboxymethylcellulose, and the very high molecular weight polyethylene oxides; a sudsing agent such as sodium lauryl sulfate or sodium lauryl sarcosinate; and a flavoring agent.

' In the following example, all parts are by weight unless otherwise specified.

Example Into a conventional stainless steel powder blending vessel are poured 10,000 parts of 200 mesh dicalcium orthophosphate dihydrate which has been stabilized with a small amount of tetrasodium pyrophospha-te, and 158 parts of '200 mesh sodium monofluorophosphate. The resulting mixture is then blended for a period of about 1 hour. The resulting uniform blend (containing 98.44 weight percent of dicalcium orthophosphate dihydrate and 1.56 weight percent of sodium monofluorophosphate) is then incorporated into a toothpaste composition in the following manner:

A powder phase is prepared by intermixing 483 parts of the abrasive-monofluorophosphate composition prepared in accordance with the above-described procedure, 1 part of saccharin, and 16 parts of gum tragacanth. These powders are blended together for about 30 minutes. Then, to one third of the resulting blended powder phase in a conventional stainless steel sigma-blade mixer, 165 parts of a mixture containing equal amounts (by weight) of water and glycerin are added very slowly (over a period of about 30 minutes) while the resulting pasty mixture is being agitated. Subsequently, over an additional 30 minute period, the remaining two-thirds of the blended powder phase and 325 parts of the glycerine-water mixture are added to the pasty mixture. The resulting pasty mixture is then stirred in the sigma-blade mixer for an additional 30 minutes to assure product uniformity. During the last 10 minutes of this latter period of agitation, 1 part of a flavoring ingredient and 16 parts of sodium lauryl sulfate are mixed into the product. The resulting toothpaste product, containing about 0.75 weight percent of sodium monofluorophosphate, is then inserted into conventional metal toothpaste tubes, which are subsequently sealed and stored at room temperature. Periodically one of the tubes is opened and analyzed to determine the amount of fluorine remaining in an available (unreacted with the other ingredients so as to remain soluble in the water when 10 parts of the paste are stirred into parts of distilled water at room temperature for about 1 hour) condition.

After being stored for a total of about 168 days, a toothpaste formulation such as that prepared in accordance with the foregoing example is found to retain as much as 55 percent of its original available (water-soluble) fluorine. A similar toothpaste, prepared in the same manner, but using an equivalent amount (based on F) of stannous fluoride in place of the sodium monofluorophosphate retains, in available form, only about 25 percent of its original fluoride after 168 days of storage at room temperature. Similarly, a formulation, prepared as in the foregoing example, containing calcium pyrophosphate in place of the dicalcium orthophosphate is found to retain only about 22 percent of its original available fluorine after 168 days of storage at room temperature.

While the foregoing example is directed to a cold procedure for manufacturing the toothpaste, conventional hot methods can also be used successfully to prepare the surprisingly compatible dentifrice compositions of the present invention.

What is claimed is:

1. A toothpaste composition containing from about 20% to about 60%, by weight, of an abrasive material and from about 0.2% to about 2.0%, by weight, of sodium monofluorophosphate; said abrasive material consisting of dicalcium orthophosphate and being characterized by having a particle size small enough to pass through a No. 20 mesh U.S. Standard screen.

2. A tooth powder composition containing from about 20% to about 95% by Weight of an abrasive material and from about 0.2% to about 2.0% by weight of sodium monofluorophosphate; said abrasive material consisting of dicalcium orthophosphate dihydrate and being characterized by having particles small enough to pass through a No. 200 mesh US Standard screen.

3. A dentifrice composition containing from about 20% to about 95% by weight of an abrasive material and from about 0.2% to about 2.0% by weight of sodium monofluorophosphate; said abrasive material consisting of a dicalcium orthophosphate selected from the group consisting of dicalcium orthophosphate dihydrate, anhydrous dicalcium orthophosphate, and mixtures thereof, the particles of said dicalcium orthophosphate being small enough to pass through a No. 200 mesh US. Standard screen.

4. A dentifrice composition as set forth in claim 3 wherein said dicalcium orthophosphate is in the form of the dihydrate.

References Cited by the Examiner LEWIS GOTTS, Primary Examiner.

20 FRANK CACCIAPAGLIA, 111., ELBERT L. ROBERTS,

Examiners.

RICHARD L. HUFF, Assistant Examiner. 

1. A TOOTHPASTE COMPOSITION CONTAINING FROM ABOUT 20% TO ABOUT 60%, BY WEIGHT OF AN ABRASIVE MATERIAL AND FROM ABOUT 0.2% TO ABOUT 2.0%, BY WEIGHT, OF SODIUM MONOFLUOROPHOSPHATE; SAID ABRASIVE MATERIAL CONSISTING OF DICALCIUM ORTHOPHOSPHATE AND BEING CHARACTERIZED BY HAVING A PARTICLE SIZE SMALL ENOUGH TO PASS THROUGH A NO. 200 MESH U.S. STANDARD SCREEN. 